Interview Questions on DSP - Open Thread - Please Contribute

• Aug 8, 2006

• #1

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naresh850

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dsp interview questions

hi,
Most of you must've already passed that interview stage and some others could be the Interviewers themselves. So, I thought this thread should be helpful to everyone and anyone who is not just attending an interview but wants to know more about DSP.

The aim is simple:

If you've come across some question that you think is tricky, please post it here along with its solution by maintaining a number to it...

Just put the question in the quote tags like this

"what is the convolution"
"y we use Forrier transform in DSP"

the answer should be that mush short. we can tell the interviwer in quik.

Please contribute as even one question from you might change someone'e life out there...

hopw we do the good job.

 

• Aug 8, 2006

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amit_8561

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dsp interview question and answers

"what is use of windowing in digital filters"

 

• Aug 9, 2006

• #3

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radheshbhat

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signal processing interview questions

"What are basis vectors in a transofrm?"

 

• Aug 10, 2006

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digital signal processing interview questions

In signal processing, why we are much more interested in orthogonal transform?

 

• Aug 11, 2006

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itsthetimetodisco

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interview questions on dsp

"What are the pros and cons of Discrete Cosine Transform?"

 

• Aug 13, 2006

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itsthetimetodisco

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dsp interview question

"What is Gibbs phenomenon?"

 

• Aug 14, 2006

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nagacnu

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dsp engineer interview questions

what is the special about minimum phase filter ?

 

• Aug 14, 2006

• #8

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naresh850

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dsp interview

Thank u all friends,
for sending the questions & spending yr valuable time.


But this forum is not only for questions.U have to share your incridible answer to others. So everyone will get benifit from it.

Post as many questions as u know.

Hope we will do that.

regards

Added after 6 minutes:

Hi,

"What is Gibbs phenomenon?"


transfer function h in time domain is infinite.
We can not implement it on DSP processor. We have to truncate it to finite lenth.

so when we truncate it. in freq domain we get the ringging at the edges.
this is called the gibbes Phenomena.

if someone have better answer then plz share to otheres.

Added after 11 minutes:


"what is use of windowing in digital filters"

because of gibbes phenomena, we get pass band ripples & stop band attenuation.

we have to remove this, we use window function.

so, different type of window we multiply with h.

 

• Aug 30, 2006

• #9

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naresh850

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dsp programming interview questions

Hi friends,

plz share yr experince.

regards,

 

• Aug 30, 2006

• #10

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interview question on dsp

use this program: [x,fs]=wavread('1.wav');
o(1:100,1)=0
a=100*ceil (length(x)/100)
l=a+200
sum(1:l,1)=0
b=a-length(x)+100
oo(1:b,1)=0
x=[o;x;oo]
ham2=hamming(200)
ham2(201:l)=0
u=x.*ham2
u=u(1:200)
fff=fft(u,1024)
fff(129:897)=0
iff=ifft(fff,1024)
iff=iff(1:200)
sum(1:200)=iff
ham=hamming(200)
m(1:a-100,1)=0

for k=1a/100+1)
n((100*k-99):100*k,1)=0
m=m(1l-100*k-200),1)
ham1=[n;ham;m]
y=x.*ham1
y=y(100*k+1100*k+200))
fff=fft(y,1024)
fff(129:897)=0
iff=ifft(fff,1024)
iff=iff(1:200)
sum((100*k+1)100*k+200))=sum((100*k+1)100*k+200))+iff(1:200)







for k=1a/100+1)

z=x(100*k+1:100*k+200)
y=z.*ham

fff=fft(y,1024)
fff(129:897)=0
iff=ifft(fff,1024)
iff=iff(1:200)
sum((100*k+1)100*k+200))=sum((100*k+1)100*k+200))+iff(1:200)

 

• Sep 19, 2006

• #11

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smileysam

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dsp engineer interview

why we use DCT extensilvely in compression?

why after DCt we use a zig zag manner for run length coding?

 

• Sep 19, 2006

• #12

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icyabhi

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interview dsp questions

Why do we need I&Q signals?

 

• Sep 20, 2006

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asnivas

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interview questions on digital signal processing

Why is FFT faster than DFT? what is the actual concept behind this?

 

• Sep 21, 2006

• #14

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shameem

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interview questions in digital signal processing

What is the basic difference blw FIR and IIR filters?
If a have two vectors, how will i check the orthogonality of those vectors?

 

• Sep 21, 2006

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narfnarf

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dsp interview questions and answers

"differences b/w butterworth, chebyshev, elliptical filter and advantages/disadvantages of each"

 

• Sep 24, 2006

• #16

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dsp filters interview questions

"What is the concept of stability of an LTI system? How to check if a given system is stable?"

 

• Sep 24, 2006

• #17

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digital signal processor interview questions

The original poster asked for answers so I repeat some of the earlier questions (and add some new) with answers.

Q. How can you determine the stability of an LTI system
A. Determine the roots of the system. If all roots have real part < 0, the system is stable. Any root has real part > 0, the system is unstable.

Q. What is aliasing and how do we prevent it.
A. Aliasing is frequency shifting of content of input signal above half the sample frequency. We avoid it by using antialiasing filters to limit signal content below 1/2 sample frequency and/or by sampling at high enough frequency to avoid antialiasing.

Q. Explain using convolution the effects of taking an FFT of a sampe with no windowing (rectangular window).
A. The signal is multiplied by a rectangular window in the time domain. This corresponds to convolution by a sync function in the frequency domain. The wide center lobe of the sync function spreads frequencies and the side lobes shift frequencies.

 

• Sep 24, 2006

• #18

Robinenemy

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dsp firmware interview questions

1. What is the need of Digital Signal Processing?
2. Why is the need of FFT ?

 

• Oct 8, 2006

• #19

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naresh850

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signal processing interview question

hi

1. wat care should be taken when we doing camulative decimation

 

• Oct 13, 2006

• #20

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digital signal processing question for interview

I have a very important question.
What is the importance of time frequency resolution? Can this be explained with respect to some application eg when we need to determine the stationary and dynamic characteristic of a signal, how do transform with different time frequency resolution, affects it. I do not want simple and vague explanation given in textbooks. I require correct and precise information.